In this work, we present a numerical solver for the simulation of an Organic Rankine Cycle (ORC) based on Scilab. The model is developed for estimating the operative conditions of the ORC system and its efficiency. ORC technologies are widely used for simultaneous production of electrical and thermal energy (a.k.a. cogeneration). These systems can provide a clean alternative to fossil fuels. For instance, cycles based on wood-burning cogeneration offer the advantage of clean elimination of wood
wastes. This version of the ORC simulator is meant for stationary analysis since the primary goals are components sizing and performance analysis of the cycle at operative conditions. The ORC simulator can be customized to meet additional needs. For example, it provides several organic and cooling fluids and different kinds of heating oils, but others can be easily added.